The present invention relates to building materials generally, and more specifically to frames suitable for use in ventilation screen assemblies.
Ventilation screen frame assemblies are well known. Joining four sections of roll-formed or extruded screen bar material, using four corner keys to attach each pair of consecutive frame members forms a typical frame.
U.S. Pat. No. 3,097,684 to Le Tarte shows an alternative method of forming a screen frame using a single elongated piece of screen bar stock. Four V-shaped cuts are cut partially through the body, each V-shaped cut leaving an edge of the body uncut. Each V-shaped cut subtends an angle of 90 degrees. The body is folded about each uncut edge so that the ends of the body meet along one side of the frame. The ends of the body are joined to form a closed frame.
A method of forming a stronger frame is desired.
One aspect of the present invention is a frame for a ventilation screen-frame assembly. The assembly includes a body having a mounting surface for receiving ventilation screen material. The body has one or more V-shaped cuts partially through it. Each V-shaped cut leaves an edge of the body uncut. The body is folded about each uncut edge so that the ends of the body meet. Each V-shaped cut subtends an angle xcex8 that is slightly less than 90 degrees, so that the folded corners are in compression. The assembly further includes means for joining the ends of the body into a closed frame.
Another aspect of the invention is a method for forming a frame for a ventilation screen-frame assembly. A body is provided having a mounting surface for receiving ventilation screen material. At least three V-shaped cuts are cut partially through the body, each V-shaped cut leaving an edge of the body uncut. Each V-shaped cut subtends an angle xcex8 that is slightly less than 90 degrees. The body is folded about each uncut edge so that the ends of the body meet, so that the folded corners are in compression. The ends of the body are joined to form a closed frame.
Another aspect of the invention is a method for forming a ventilation screen-frame assembly, comprising the steps of: forming a body having a mounting surface for receiving ventilation screen material; heating the body; inserting a hot melt adhesive in a groove of the body; cutting at least three V-shaped cuts partially through the body, each V-shaped cut leaving an edge of the body uncut; folding the body about each uncut edge so that the ends of the body meet; joining the ends of the body to form a closed frame; transferring the frame directly to an insertion apparatus without cooling the frame; and inserting screen cloth into the hot melt adhesive.
Yet another aspect of the invention is a frame for a ventilation screen-frame assembly, comprising: a pair of elongate bodies, each having a mounting surface for receiving ventilation screen material. Each body has a V-shaped cut partially therethrough. Each V-shaped cut leaves an edge of the body uncut. The bodies are folded about each uncut edge so that each V-shaped cut subtends an angle xcex8 that is slightly less than 90 degrees, and the folded corners are in compression. The two bodies are arranged so as to form a four sided frame with the ends of the bodies meeting at corners of the bodies. Means are provided for joining the ends of the bodies into a closed frame.
Another aspect of the invention is a ventilation screen-frame assembly, comprising a body having a mounting surface for receiving ventilation screen material. The body has at least three V-shaped cuts partially therethrough. Each V-shaped cut leaves an edge of the body uncut. The body is folded about each uncut edge so that the ends of the body meet. The body has a radius of curvature of about 50 meters while the body is in an unstressed state. Means are provided for joining the ends of the body into a closed frame. Ventilation screen cloth is tensioned by and mounted to the frame, so that the sides of the frame are held substantially straight by the screen cloth, and the body is in compression at each folded corner.
These and other aspects of the invention are described below with reference to the drawings and the exemplary embodiments.